Scrapers are commonly used for cleaning surfaces especially for removing paint, adhesives or other materials from surfaces which are essentially flat and smooth. For many years scrapers have been known with blades that can be moved between an extended position when in use and a protected or retracted position when not is use. Examples of such scrapers are shown in U.S. Pat. No. 4,558,517 or U.S. Pat. No. 4,955,138.
The common solution for moving the scraper blade between the extended and the retracted position is a trigger that can be located at the top of the scraper. This trigger is connected to a movable part of the scraper which is securely connected to the scraper blade. This allows the scraper blade to be moved in and out of the scraper casing by operating the trigger forward and back on the tool. The trigger is operated by using the thumb or another finger and requires the operator to apply pressure to move the trigger forward. In order to prevent the user from the need of exerting a permanent force on the trigger to keep the scraper blade in the extended position a lock mechanism is commonly used, which keeps the scraper blade in the extended position until the task is finished and the scraper blade can be stowed back into the retracted position. Depending on the type of mechanism used for locking the scraper in the extended position an additional force is required to move the scraper blade into and out of this position. For example it may be required to use the second hand to turn a knob fixing the scraper blade in the extended position as shown in U.S. Pat. No. 8,291,598. Alternately the trigger may be constructed in a way that it contains a mechanism that locks in either the retracted or the extended position as shown in U.S. Pat. No. 8,171,646. In this case the scraper blade slide must be disengaged by applying an additional force on the trigger for moving the scraper blade slide.
In U.S. Pat. No. 6,775,912 a solution is shown where only one trigger is used for moving the scraper blade slide from the retracted to the extended position and back. In this case an additional force perpendicular to the moving direction of the scraper blade is required to disengage the scraper blade slide from one of the two predefined positions before it can be moved to the other position.
In cases where the scraper is operated back and forth between the extended and the retracted position many times the operators thumb and fingers will tire quickly, as a force must be applied in forward and downward for moving the scraper blade to the extended position for using the scraper hand tool and backward and downward again after use for storing the scraper blade back in the protected position. Also as the scraper blade must be actively moved back to the retracted position, it is likely the operator will leave the scraper blade in the extended position, thus increasing the risk of injury.